Hydrodynamic bearing assembly and method of assembling the same

ABSTRACT

A hydrodynamic bearing assembly includes a first member including a first engaging surface. The first member is stationary in a non-operating mode of the bearing assembly and rotates about an axis in an operational mode of the bearing assembly. The hydrodynamic bearing assembly also includes a second member including a bore and a second engaging surface positioned adjacent the first engaging surface. The second member is stationary in both the non-operating mode and the operational mode of the bearing assembly. The hydrodynamic bearing assembly further includes a spacer member positioned within the bore and is configured to engage the first member to define a first gap between the first engaging surface and the second engaging surface in the non-operational mode.

BACKGROUND

The field of the disclosure relates generally to hydrodynamic bearings, and more specifically, to a hydrodynamic bearings assembly that improves service lifetime of the hydrodynamic bearing.

At least some known hydrodynamic bearings include a stationary member and a rotating member. In operation, the bearing load is supported by a thin layer of rapidly moving pressurized liquid or gas between opposing surfaces of the stationary and rotating members. Because the two members are separated by the layer of fluid in operation, there is no contact between the moving parts, and the bearing has lower friction, wear and vibration than many other types of bearings. Such bearings are frequently used in high load, high speed or high precision applications where ordinary ball bearings would have short life or cause high noise and vibration.

However, the opposing faces of the stationary and rotating members do contact each other both when the bearing is non-operational and also for a duration after rotation initialization before the rotating member lifts away from the stationary member. During low speed rotation, the two members contact each other and cause large friction forces between the two faces. Such friction forces may shorten the service lifetime of the bearing and may also generate undesirable noise.

BRIEF DESCRIPTION

In one aspect, a hydrodynamic bearing assembly is provided. The hydrodynamic bearing assembly includes a first member including a first engaging surface. The first member is stationary in a non-operating mode of the bearing assembly and rotates about an axis in an operational mode of the bearing assembly. The hydrodynamic bearing assembly also includes a second member including a bore and a second engaging surface positioned adjacent the first engaging surface. The second member is stationary in both the non-operating mode and the operational mode of the bearing assembly. The hydrodynamic bearing assembly further includes a spacer member positioned within the bore and is configured to engage the first member to define a first gap between the first engaging surface and the second engaging surface in the non-operational mode.

In another aspect, a method of assembling a hydrodynamic bearing assembly is provided. The method includes providing a first member having a first engaging surface. The first member is stationary in a non-operating mode of the bearing assembly and rotates about an axis in an operational mode of the bearing assembly. The method also includes positioning a second member having a second engaging surface adjacent the first member. The second member is stationary in both the non-operating mode and the operational mode of the bearing assembly. The method further includes coupling a spacer member within a bore defined in the second member such that the spacer member engage the first member in the non-operational mode to define a first gap between the first engaging surface and the second engaging surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, partially exploded view of an exemplary hydrodynamic bearing assembly;

FIG. 2 is a cross-sectional view of the hydrodynamic bearing assembly shown in FIG. 1 in a non-operational mode;

FIG. 3 is an enlarged cross-sectional view of the portion hydrodynamic bearing assembly indicated by box 3-3 in FIG. 2 in an operational mode;

FIG. 4 is a cross-sectional view of an alternative embodiment of a hydrodynamic bearing assembly in a non-operational mode;

FIG. 5 is an enlarged cross-sectional view of the hydrodynamic bearing assembly shown in FIG. 4 in an operational mode; and

FIG. 6 is a cross-sectional view of an alternative embodiment of a hydrodynamic bearing assembly.

Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing.

DETAILED DESCRIPTION

FIG. 1 is a perspective, partially exploded view of an exemplary hydrodynamic bearing assembly 100, FIG. 2 is a cross-sectional view of hydrodynamic bearing assembly 100 in a non-operational mode 102, and FIG. 3 is an enlarged cross-sectional view of hydrodynamic bearing assembly 100 in an operational mode 104. In the exemplary embodiment, assembly 100 includes a first member 106 positioned adjacent to a second member 108. First member 106 includes a body portion 110 and a plate 112 coupled to body portion 110. Similarly, second member 108 includes a body portion 114 and a plate 116 coupled to body portion 114. Plate 112 includes a first engaging surface 118 that is positioned adjacent a second engaging surface 120 of plate 116. In the non-operational mode, both first member 106 and second member 108 are stationary. However, in the operational mode, first member 106 rotates about an axis 122, and second member 108 remains stationary. The rotation of first member 106 pressurizes a fluid (not shown) between surfaces 118 and 120 and causes first member 106 to move axially away from second member 108.

In the exemplary embodiment, assembly 100 also includes a spacer member 124 coupled within a bore 126 defined through body 114 and plate 116. As shown in FIG. 2, spacer member 124 engages first member 106 to define a first gap 128 between surfaces 118 and 120 in the non-operational mode. More specifically, a tip 129 of spacer member 124 engages first engaging surface 118 of first member plate 112 such that spacer member 124 and surface 118 contact each other when assembly 100 is in the non-operational mode. Even more specifically, first engaging surface 118 includes a recess 130 formed therein, and spacer tip 129 contacts a surface 132 of recess 130 in the non-operational mode. In one embodiment, when members 106 and 108 are stationary, in the non-operational mode, spacer member 124 spaces apart engaging surfaces 118 and 120 such that gap 128 is defined therebetween. Accordingly, spacer member 124 receives the axial load within bearing assembly 100 rather than the axial load being imparted onto engaging surfaces 118 and 120. In the exemplary embodiment, spacer member 124 includes a jewel bearing. Alternatively, spacer member 124 includes any type of spacer that facilitates operation of bearing assembly 100 as described herein. Furthermore, in the exemplary embodiment, tip 129 is a point of spacer member 124. Alternatively, in another embodiment, tip 129 includes any shape or profile, such as but not limited to, a flat surface, a dome, or a sphere that enables spacer member to operate as described herein.

When bearing assembly 100 shifts from non-operational mode 102 to operational mode 104, first member 106 begins to rotate about axis 122. In the exemplary embodiment, gap 128, created by spacer member 124, spaces first engaging surface 118 from against second engaging surface 120 to reduce contact between surfaces 118 and 120. Furthermore, spacer member 124 supports first member 106 for a short duration in operational mode 104 until first member 106 reaches a speed that causes first member to move farther away from second member 108. In one embodiment, spacer member 124 keeps engaging surface 118 and 120 separate during initial start-up of bearing assembly 100, thereby reducing initial spinning torque and wear on plates 112 and 116 caused by friction in some known bearing assemblies.

As described herein, in the operational mode 104, rotation of first member 106 pressurizes the fluid within bearing assembly 100, between surfaces 118 and 120, and causes first member 106 to “lift” or move away from second member 108 to define a second gap 134 between first engaging surface 118 and second engaging surface 120. In one embodiment, second gap 134 is larger than first gap 128 (shown in FIG. 2). Furthermore, the rotational lifting of first member 106 also defines a third gap 136 between spacer member 124 and first member 106. More specifically, third gap 136 is defined between spacer member 124 and first engaging surface 118. Even more specifically, third gap 136 is defined between spacer member tip 129 and surface 132 of recess 130 formed in first engaging surface 118.

In the exemplary embodiment, in operational mode 104, recess 130 and first engaging surface 118 of first member 106 are spaced away from tip 129 of spacer member 124 and second engaging surface 120 of second member 108, respectively. In operational mode 104, the axial load is carried by first member 106, second member 108, and the pressurized fluid between engaging surfaces 118 and 120.

FIG. 4 is a cross-sectional view of another embodiment of a hydrodynamic bearing assembly 200 in a non-operational mode 202, and FIG. 5 is an enlarged cross-sectional view of the portion of hydrodynamic bearing assembly 200 indicated by box 5-5 in FIG. 4 in an operational mode 204. In the exemplary embodiment, assembly 200 includes a first member 206 positioned adjacent a second member 208. First member 206 includes a body portion 210 and a plate 212 coupled to body portion 210. A bore 211 is defined through both body portion 210 and plate 212. Similarly, second member 208 includes a body portion 214 and a plate 216 coupled to body portion 214. Plate 212 includes a first engaging surface 218 that is positioned adjacent a second engaging surface 220 of plate 216. In the non-operational mode, both first member 206 and second member 208 are stationary. However, in the operational mode, first member 206 rotates about an axis 222, and second member 208 remains stationary. The rotation of first member 206 pressurizes a fluid (not shown) between surfaces 218 and 220 and causes first member 206 to move axially away from second member 208.

In the exemplary embodiment, assembly 200 also includes a spacer member 224 coupled within a bore 226 defined through body 214 and plate 216 of second member 208. Furthermore, first member 206 includes a shaft 225 coupled within bore 211. As shown in FIG. 2, shaft 225 extends beyond first engaging surface 218 and into bore 226 of second member 208 such that an end surface 227 of shaft 225 is positioned within bore 226. Alternatively, shaft 225 terminates before reaching first engaging surface 118 such that end surface 227 is positioned within bore 211. Generally, shaft 225 extends any length that facilitates operation of bearing assembly 200 as described herein.

In the exemplary embodiment, spacer member 224 engages first member 206 to define a first gap 228 between surfaces 218 and 220 in the non-operational mode. More specifically, a tip 229 of spacer member 224 engages shaft 225 of first member 206 such that spacer member 224 and shaft 225 contact each other when assembly 200 is in the non-operational mode. Even more specifically, tip 229 of spacer member 224 engages end surface 227 of shaft 225 such that spacer member 224 and shaft end surface 227 contact each other when assembly 200 is in the non-operational mode. In one embodiment, when members 206 and 208 are stationary, in the non-operational mode, spacer member 224 separates engaging surfaces 218 and 220 such that gap 228 is defined therebetween. Accordingly, spacer member 224 receives the axial load within bearing assembly 200 rather than the axial load being imparted onto engaging surfaces 218 and 220. In the exemplary embodiment, spacer member 224 includes a jewel bearing. Alternatively, spacer member 224 includes any type of spacer that facilitates operation of bearing assembly 200 as described herein.

When bearing assembly 200 shifts from non-operational mode 202 to operational mode 204, as shown in FIG. 5, first member 206 begins to rotate about axis 222. Gap 228, created by spacer member 224, spaces first engaging surface 218 from second engaging surface 220 to reduce contact between surfaces 218 and 220. Furthermore, spacer member 224 supports first member 206 for a short duration in operational mode 204 until first member 206 reaches a speed that causes first member to move farther away from second member 208. Spacer member 224 keeps engaging surface 218 and 220 separate during initial start-up of bearing assembly 200, thereby reducing initial spinning torque and wear on plates 212 and 216 caused by friction in some known bearing assemblies.

As described herein, in the operational mode 204, rotation of first member 206 pressurizes the fluid within bearing assembly 200, between surfaces 218 and 220, and causes first member 206 to “lift” or move away from second member 208 to define a second gap 234 between first engaging surface 218 and second engaging surface 220. In one embodiment, second gap 234 is larger than first gap 228 (shown in FIG. 4). Furthermore, the rotational lifting of first member 206 also defines a third gap 236 between spacer member 224 and first member 206. More specifically, third gap 236 is defined between spacer member 224 and shaft 225. Even more specifically, third gap 236 is defined between spacer member tip 229 and end surface 227 of shaft 225.

In the exemplary embodiment, in operational mode 204, shaft 225 and first engaging surface 218 of first member 206 are spaced away from tip 229 of spacer member 224 and second engaging surface 220 of second member 208, respectively. In operational mode 204, the axial load is carried by first member 206, second member 208, and the pressurized fluid between engaging surfaces 218 and 220.

FIG. 6 is a cross-sectional view of a hydrodynamic bearing assembly 200 in non-operational mode 202 and including a biasing mechanism 238. As shown in FIG. 6, biasing mechanism 238 is positioned within bore 226 and is coupled to spacer member 224. Biasing mechanism 238 supports spacer member 224 within bore 226 such that when first member 206 is positioned adjacent second member 208, biasing mechanism 238 compresses to receive at least a portion of the axial load carried by spacer member 224. More specifically, the axial load of first member 206 imparted on spacer member tip 229 by shaft 225 causes biasing mechanism 238 to compress. Such compression causes spacer member 224 to move a distance into bore 226 while still maintaining first gap 228 between surfaces 218 and 220. As rotation begins in the operational mode 204 and first member 206 moves away from second member 208, the axial load on spacer member 224, and biasing mechanism 238, is decreased such that biasing mechanism 238 extends from its compressed state and spacer member 224 moves axially within bore 226. As the rotational speed of first member 206 increases, the distance between surfaces 218 and 220 continues to increase until first member 206 lifts away from spacer member 224 to define third gap 236 (shown in FIG. 5.

Although biasing mechanism 238 is shown and described as a component of bearing assembly 200, it is contemplated that bearing assembly 100 (shown in FIGS. 1-3) may also include biasing mechanism 238 coupled to spacer member 124 that carries at least a portion of the axial load imparted onto spacer member 124 by engaging surface 118 rather than by shaft 225, as in bearing assembly 200.

The apparatus, methods, and systems described herein provide a hydrodynamic bearing assembly having reduced wear and increased service lifetime. More specifically, the spacer member described herein facilitates defining a gap between opposing engaging surfaces of the bearing members when the bearing members are stationary and during relatively low speed rotation. In one embodiment, the gap between the engaging surfaces spaces the surfaces from each other at initial start-up to reduce contact between the surfaces. The bearing assembly described herein does not generate high frictional forces or torque at start-up. Accordingly, the bearing members have an increased service lifetime and also generate less noise and vibrations as compared to at least some known hydrodynamic bearing assemblies. Once the rotating bearing member reaches a certain speed, it lifts away from the spacer member to increase the size of the gap between opposing engaging surfaces and to define a gap between the spacer member and the rotating member. In the operational mode, the bearing members do not contact each other and the axial load is carried by the pressurized fluid layer between the two bearing members.

Exemplary embodiments of the hydrodynamic bearing assembly are described above in detail. The hydrodynamic bearing assembly and its components are not limited to the specific embodiments described herein, but rather, components of the systems may be utilized independently and separately from other components described herein. For example, the components may also be used in combination with other machine systems, methods, and apparatuses, and are not limited to practice with only the systems and apparatus as described herein. Rather, the exemplary embodiments can be implemented and utilized in connection with many other applications.

Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.

This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A hydrodynamic bearing assembly comprising: a first member comprising a first engaging surface, wherein said first member is stationary in a non-operating mode of said bearing assembly and wherein said first member rotates about an axis in an operational mode of said bearing assembly; a second member comprising a bore and a second engaging surface positioned adjacent said first engaging surface, wherein said second member is stationary in both the non-operating mode and the operational mode of said bearing assembly; and a spacer member positioned within said bore and configured to engage said first member to define a first gap between said first engaging surface and said second engaging surface in the non-operational mode, wherein said spacer member extends into said first gap.
 2. The hydrodynamic bearing assembly in accordance with claim 1, wherein a second gap is defined between said first engaging surface and said second engaging surface in the operational mode, said second gap being larger than said first gap.
 3. The hydrodynamic bearing assembly in accordance with claim 2, wherein said spacer member is spaced from said first member in the operational mode such that a third gap is defined between said spacer member and said first member.
 4. The hydrodynamic bearing assembly in accordance with claim 1, wherein said spacer member is configured to engage said first engaging surface in said non-operational mode.
 5. The hydrodynamic bearing assembly in accordance with claim 4, wherein said first engaging surface comprises a recess formed therein, and said spacer member is configured to engage said recess in said non-operational mode.
 6. The hydrodynamic bearing assembly in accordance with claim 4, wherein said spacer member is spaced from said first engaging surface in the operational mode.
 7. The hydrodynamic bearing assembly in accordance with claim 1, wherein said first member comprises a bore and a shaft positioned within said bore, said shaft comprising an end surface.
 8. The hydrodynamic bearing assembly in accordance with claim 7, wherein said spacer member is configured to engage said shaft end surface in said non-operational mode.
 9. The hydrodynamic bearing assembly in accordance with claim 8, wherein said spacer member is spaced from said shaft end surface in the operational mode.
 10. The hydrodynamic bearing assembly in accordance with claim 1, wherein said second member comprises a biasing mechanism positioned within said bore and configured to be coupled to said spacer member.
 11. The hydrodynamic bearing assembly in accordance with claim 10, wherein said biasing mechanism is configured to receive at least a portion of an axial load imparted by said first member on said spacer member in the non-operational mode.
 12. A method of assembling a bearing assembly, said method comprising: providing a first member having a first engaging surface, wherein the first member is stationary in a non-operating mode of the bearing assembly and wherein the first member rotates about an axis in an operational mode of the bearing assembly; positioning a second member having a second engaging surface adjacent the first member; wherein the second member is stationary in both the non-operating mode and the operational mode of the bearing assembly; and coupling a spacer member within a bore defined in the second member such that the spacer member engages the first member in the non-operational mode to define a first gap between the first engaging surface and the second engaging surface, wherein the spacer member extends into the first gap.
 13. The method in accordance with claim 12, wherein coupling the spacer member within the bore comprises coupling the spacer member such that a second gap is defined between the first engaging surface and the second engaging surface in the operational mode, wherein the second gap is larger than the first gap.
 14. The method in accordance with claim 12, wherein coupling the spacer member within the bore comprises coupling the spacer member such that a third gap is defined between the spacer member and the first member in the operational mode.
 15. The method in accordance with claim 12, wherein coupling the spacer member within the bore comprises coupling the spacer member to engage the first engaging surface in the non-operational mode and such that the spacer member is spaced from the first engaging surface in the operational mode.
 16. The method in accordance with claim 15, wherein coupling the spacer member within the bore comprises coupling the spacer member to engage a recess formed in the first engaging surface in the non-operational mode.
 17. The method in accordance with claim 12, further comprising coupling a shaft within a bore defined through the first member such that the shaft extends into the second member bore.
 18. The method in accordance with claim 17, wherein coupling the spacer member within the bore comprises coupling the spacer member to engage an end surface of the shaft in the non-operational mode.
 19. The method in accordance with claim 18, wherein coupling the spacer member within the bore comprises coupling the spacer member such that the spacer member is spaced from the shaft end surface in the operational mode. 